Vulnerability Details CVE-2026-91769
PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 3.0%
CVSS Severity
CVSS v3 Score 4.3